Analysis of the Sound Field Changes in Railway Tunnel by Incorporating Porous Aggregate Sound Absorbing Materials

Abstract

While travelling through railways, passengers are often subjected to a train’s interior noise. Compared to an open area, such noise increases when a train passes through a tunnel because the interior of the tunnel generally comprises a concrete surface with a very low rate of sound absorption, and the noise from railway vehicles undergoes multiple reflections inside the tunnel. To reduce a train’s interior noise while passing through a tunnel, it is necessary to analytically and experimentally study the noise reduction effect caused by incorporating high strength porous aggregate sound absorbing materials that satisfy the material performance standards required by railway facilities. Acoustic simulation of the sound field within a tunnel has been previously analyzed for predicting the noise reduction caused by porous aggregate sound absorbing materials, before and after installation. Furthermore, the sound absorption performance in the space between the installation section and the non-installation section has been compared by measuring the reverberation time after incorporating sound absorbing materials in an actual test tunnel. In this study, a method for efficient arrangement of sound absorbing materials is proposed based on the sound field analysis results of railway tunnels. The proposed study can thus provide fundamental data for further research on aspects such as sound insulation design for railway vehicle body and railway infrastructure. Key words: Railway Tunnel, Train Interior Noise, Sound Absorbing Material, Acoustic Analysis, Reverberation Time